That's a bizarre and backward way to look at it. In a growth company, employees provide value in a lot of indirect, but important, ways. Having employees speak at conferences is a very common recruiting tactic; often, good people are at conferences, and when they hear about a great company to work for with smart people who give good talks, they want to work there, too. Books are similar. Reading Site Reliability Engineering makes me want to work at Google (even though I know I really don't want to work at Google).

Good people bring in more good people, and good people are enthusiastic and do cool things outside of work. The author is probably someone I'd want to work with, based on her enthusiasm for her job and her obviously effective time management (I wrote a technical book once, and it took a year longer than I'd planned). The people who convinced someone like her to leave a place are people I definitely wouldn't want to work with.

I suppose my in my life I have found people with ~20 months of real-world experience who write books about technical topics in domains which are well understood... are kind of problematic.

Sure, sending out your experts with 5+ years experience in a specific field is great evangelism. But that's not what's being discussed here.

So, you're saying she isn't competent to write a book or give talks, despite the fact that she's written a book for a publisher with a very good reputation for high standards and has been hired by two top tier tech companies to work in the field.

On what do you base your assertion that she is incompetent?

Having external recognition including speaking and writing can be part of the promotion requirements. They were certainly in mine when I was at Yahoo.